The present invention relates to an air jet nozzle which is adapted for use in the treatment of running multifilament textile yarns, and wherein a running yarn composed of continuous synthetic filaments is subjected to a high velocity airstream to impart spaced entanglements to the yarn.
The process known in the textile industry as intermingling or entangling is commonly employed to improve the handling and coherence of zero twist continuous filament yarn, while permitting the expensive twisting step to be eliminated. The process is suitable for the treatment of flat as well as texturized synthetic yarns, including yarns composed of glass or polymeric filaments.
Prior art jet nozzles of this general type typically include a cylindrical yarn passageway and a radial air inlet channel communicating with the passageway. Compressed air under a pressure of about 6 bar is fed to the air inlet channel, and as the running yarn is advanced through the passageway, knot-like spaced apart entanglements are formed in the yarn. The distance between such entanglements, and their stability, are important quality features of the process, and factors which affect these quality features include the running yarn speed, and the denier of the yarn and of the filaments.
Some of the prior known nozzles of this type incorporate a yarn threading slot which opens into the yarn passageway, and extends along a plane which includes the axis of the yarn passageway. A yarn threading slot is considered essential in cases where the yarn is supplied continuously and at high speed, such as in spinning, spin-drawing, and spin-draw-texturing processes for synthetic yarns. The prior art jet nozzles which incorporate a threading slot typically comprise slotted inner and outer body members which are rotatable relative to each other. The members may be rotated to one relative position wherein the slots are in alignment to permit yarn thread up, or to another relative position wherein the slots are out of alignment. However, it has been found that with such a construction, yarns having a denier of more than about 1000 dtex, and which are supplied at a speed of at least about 2000 m/minute, particularly carpet yarns, cannot be properly entangled. The explanation for this deficiency is not totally understood, since the yarn threading slot is not positioned in the blowing direction of the air inlet, but it may be due to asymmetrical pressure gradients in the yarn passageway.
It accordingly is an object of the present invention to provide an air jet nozzle which is able to process continuous multifilament yarns so as to impart spaced entanglements to the yarns, and with the resulting yarns being adapted to run smoothly from their bobbins, under a uniform tension and without breakage.
It is also an object of the present invention to provide an air jet nozzle which is able to process such yarns in the described manner and such that the filaments of the resulting yarns have sufficient cohesion to permit subsequent processing, such as tufting.
It is a further object of the present invention to provide an air jet nozzle which may be readily threaded by means of a threading slot which does not disrupt the desired effect of the air jet during normal operation, and which is able to process yarns having a denier of more than about 1000 dtex and which are supplied at speeds greater than 2000 m/minute.